A method and an apparatus are provided for testing the efficiency of a
cleaning procedure for a filter in a filtering system. After the cleaning
procedure of the filter, the filter pores contain a fluid. The system is
pressurized, and a decay in pressure over a predetermined time period is
measured. Based on the pressure decay, it is determined whether or not
the cleaning procedure has been effective; a pressure decay smaller than
a predetermined threshold value indicates that the cleaning procedure has
not been effective.